Advanced Materials Research Vols. 919-921

Abstract: In this paper, taking symmetrical twin-tower tall building model as an example, a wind tunnel test with simultaneous surface pressure measurement, in 7 wind directions, was carried out. Integration of the surface pressures leads to base moment coefficient, of which the amplitude and frequency-domain characteristics were analyzed and compared with those of single tall building model. The result shows that mean value and root mean square of the interfering tower, in all wind directions, are basically the same as those of single tower, while in 0^o wind direction, they differ greatly; mean value and root mean square of the interfered tower differ significantly, in every wind directions, from those of single tower. In 0^o wind direction, the reduced spectrum of along-wind and across-wind base moment coefficient is greatly different from that of the single tower; in 90^o wind direction, the along-wind base moment coefficient reduced spectrum for interfered tower is different from Davenport spectrum, while the peak value of across-wind base moment coefficient is half the corresponding value of single tower.

Abstract: Working at a construction site is a dangerous job. It all depends on specific characteristics of this kind of work, the uniqueness of the construction site considering the conditions of the construction process, climatic and geographical environment, the level of difficulty of the construction work at height or in depth, the usage of heavy machines, the work with dangerous substances, the high number of simultaneous and consecutive processes constantly going on, the high number of employees, etc. That is why it is a duty of an employer to elaborate a Safety Work Plan, even before the beginning of the construction process, which is a crucial part of the project documentation. These documents need to cover all the general principles of the incident prevention concerning safety work. Also during the construction process, the systematic control is very important, covering all the specific aspects of the construction site. Safety work management means threats identification and risks assessment and risks control. The contribution deals with risk management at a construction site on the basis of the results of the risks analysis.

Abstract: The calculation of structure creep effect depends on the computational accuracy of concrete prediction model. Eight groups of test data were collected and used to evaluate six different prediction models. The differences between the calculated and the test data were analyzed. Based on the analysis, the method to improve the B3 prediction model was discussed, and the examples of revised B3 prediction model by the use of short-time tests were also presented. The results show that updating the prediction model based on short-time tests can improve the accuracy of B3 creep prediction model.

Abstract: This paper introduces the analysis of three span continuous girder arch bridge under the action of live load whose middle span is concrete filled steel tube with Ansys. Through the analysis, the deformation and the maximum displacement can be got which may provide reliable reference for further study of the arch bridge.

Abstract: Based on fuzzy decision theory, multi objective fuzzy optimization is done for three dynamic model scheme of self-anchored cable-stayed suspension bridge. Combining the fuzzy decision method with engineering practice and using two comparison theory solves the problem of quantifying the qualitative indexes. Comparison results show that it is more reasonable to place viscous dampers between main tower and girder, with longitudinal displacement on mid-span of girder on the same time. This method can provide a reference for structure selection in practical conceptual design phase.

Abstract: The monorail beam (Z206-25) of Chongqing straddle monorail transit system was selected as the research object. The spatial coupling vibration model of vehicle-bridge system was established and corresponding procedure was compiled. The effect of travelling, steering and stabilizing wheel pressure respectively and typical combined wheel pressure on the system vibration was studied. The results show that the change of wheel pressure has great effect on the response of the system. The vertical response value increases with travelling wheel pressure increasing. The lateral response value increases with steering wheel pressure increasing, while the effect of stabilizing wheel pressure on the response is irregular. The effect of steering wheel pressure is greater than that of stabilizing wheel pressure on lateral responses. The effect of all of travelling and steering wheel pressure is greater than that of unilateral wheel pressure on the response. The effect tendency of stabilizing wheel pressure on the response is opposite to that of unilateral wheel pressure.

Abstract: To accurately calculate the prestress of externally prestressed composite girder bridges, the six critical factors (the prestressing tendon withdrawal and anchor deformation, friction between prestressing tendon and deviator, prestressing tendon relaxation, concrete creep, concrete shrinkage and temperature changes) that cause the prestress loss of such type of the bridges are summarized and the corresponding simplified calculation methods are respectively derived on the basis of the existing researches. The prestressing tendons ability has an important influence on the mechanical behavior of prestressed composite girder bridges, which is the key design parameters. Prestress loss will occur in the process of long-term use, so that the whole beam stress redistribution occurs. How to accurately calculate the value of the prestressing loss is an issue of great concern to engineers. And at present there is few research for prestressed composite girder bridges. On the basis of existing research, this paper summarizes the key factors that lead to loss of prestress and derives the corresponding simplified calculation method for design reference.

Abstract: In the construction process of Hong Kong-Zhuhai-Macao Bridge, the side span girder of Qingzhou channel bridge, the non-navigable span of the shallow water region and the side span S11 ~ S17 large segments are located between transitional pier and auxiliary pier of Jiuzhou channel bridge are based on the large segment hoisting construction technique. The widely use of the large segment hoisting construction which can ensure the construction safety and shorten the construction period obviously, effectively reduce the bad environment factors in construction. All of these are important to the transportation hub, Hong Kong-Zhuhai-Macao Bridge. But because of the transformation of structural system and the complex stress of the large segment girder in the lifting point in transportation and hoisting process, it is significant to do the finite element simulation analysis.

Abstract: Larger displacement and inter-force response of the structure will be produced when self-anchored cable-stayed suspension bridge in longitudinal earthquake. The optimized layout of viscous damper is done for self-anchored cable-stayed suspension bridge with the lead rubber bearings in the main tower, moreover, the nonlinear time-history analysis in the longitudinal seismic input be made. Comparing the analysis results above between the scheme with viscous damper and the scheme without isolation measures, analysis results show that inter-force and displacement of control section and control node are reduced greatly in hybrid vibration control.

Abstract: Cantilever construction is main mode for prestressed concrete continuous rigid frame box-girder bridges, but the diagonal cracks on web are often appeared in construction. The prestressed tension is an important part of the construction beyond doubt. This article takes a bridge under construction as the background to analyze the variation of stressed in the process of construction by MIDAS FEA. The result shows that the vertical steel stretch-drawn in advance has to be a consensus in future.